Lapping device



June 28, 1932. c F B UER LAPPING DEVICE Filed March 15. 1950 INVENTOR COW/89D F 5/?656055 ATTORNEYS Patented June 28, 1932 PATENT OFFICE CONRAD F. BIRGBAUER, F DETROIT, MICHIGAN LAPPING DEVICE Application filed March 15, 1930. Serial No. 436,191.

The main objects of this invention are to provide an improved internal lapping device of the type with which abrasive materials such as diamond dust are used; to provide a :3 fabricated lap of this kind in which quantities of abrasive material are confined in close proximity to its working surface and dis tributed uniformly throughout the entire area of the working surface; to provide films of to abrasive material which are exposed at the working surface of the tool and which extend inwardly therefrom so as to present successive new areas of abrasive to the work as the working surface of the lap wears during operation; and to provide a laminated cylinder which has a composite working periphery consisting of alternate areas of metal and abrasive material.

Further objects of this invention are to provide a fabricated lap having alternate layers of abrasive material and metal which are adapted to be expanded to vary the diameter of the lap; and to provide adjustable means for securing parts of a lap of this kind in various expanded positions so as to predetermine the working diameter of the lap.

An illustrative embodiment of my invention is shown in the accompanying drawing, in which:

Fig. 1 is an elevation of a lap embodying my invention.

Fig. 2 is a horizontal section taken on the line 2-2 of Fig. 1.

Fig. 3 is a central section illustrating the arrangement in which parts of the device are placed during assembly.

Fig. 4 is a side elevation partly in section of a lap embodying a modified form of my in- A vention. v

Fig. 5 is a central section showing the parts of a lap in an unclamped position.

Fig. 6 is a horizontal section taken on the line 6-6 of Fig. 5.

Fig. 7 is a section similar to Fig. 6 showing another form of my invention.

In the form shown in Figs. 1, 2 and 3, the lap comprises a shank 1 having a shoulder 2 and a central, axially extending stem 3 at one end on which are mounted a plurality of fiat washer-like members 4;. The members 4 have a central aperture 5 for receiving the stem 3 and they are mounted thereon in superimposed relation.

Films 6 of abrasive material such as diamond dust, carborundum or emery, are located betwen adjacent faces of the members 4 in close proximity to their outer peripheries. The granular abrasive material is preferably mixed with oil, but glue or other substances having adhesive properties may be used in place of the oil. The films 6 extend inwardly a substantial distance from the outer periphery of the members 1 so as to provide successive new areas of abrasive as the peripheries of the members wear during operation. A film of adhesive may be applied on the working surface after the tool is assembled but it is not necessary that the entire face of the members be covered with the abrasive material. The members t are firmly clamped together upon the shoulder 2 of the shank 1 by a peaned head 7 which is formed on the outer end of the stem 3 after the members have been threaded thereon.

The members 4 are preferably formed of a comparatively soft metal such as bronze, copper, brass, tin, aluminum or alloys there of into which the particles of abrasive may readily'become embedded when they escape from the crevices between the members during operation. If desired, however, the washers may be formed of relatively harder metal such as cast iron and steel, and for some purposes it is advantageous to employ alternately arranged discs of hard and soft metals respectively.

The lap shown in Figs. 4, 5 and 6 comprises a stem 1 having a recess 8 and a communicating central aperture 9 in one end, the outer extremities of the wall of the recess being rounded at 10. Threaded in the recess 9 is a stem 11 having a disc-shaped head 12 on its outer end in which are formed spaced apertures 13 for receiving prongs of a tool (not shown). Mounted in superimposed relation on the stem 11 between the head 12 and the rounded wall 10 of the aperture 8 are a plurality of frusto-conical members 14: which are formed of any of the above mentioned metal. The frusto-conical members 14 each have an aperture 15 formed at their center for receiving the stem 11 and spaced radially extending notches 16 formed in their outer portions for permitting radial expansion of the members.

Films 17, consisting of an abrasive such as diamond dust, carborundum or emery and oil, are provided on the internal side of the frusto-conical members 14 in close proximity to the outer periphery thereof. These films also extend inwardly from the outer periphery so as to retain deposits of abrasive material in readiness for use as these peripheries wear.

The frusto-conical member 18 illustrated in Fig. 7 is of substantially the same shape "as the members 1 1 shown in Figs. 4, 5 and 6,

but is provided with a plurality of closely arranged radially extending slits 19 which render the member more susceptible of radial expansion. A film 20 of abrasive material is also located onthe internal surface of the member 18.

With the construction shown in each form, the lap has a fabricated cylindrical cutting part, the periphery of which is formed of alternate areas of metal and abrasive material. This construction provides a tool which may be economically produced and which has fast cutting properties. As the working surface of the tool wears, new areas of abrasive material are exposed to the work, thus prolonging the useful life of the device.

In the construction shown in- Figs. 4 to 7, inclusive, the members 14 are firmly clamped together bet ween the extremity of the shank 1 and the head 12 of the stem 11. The stem II'ma-y be screwed inwardly by a tool (not shown) having prongs which extend into the apertures 13 so as to place the members 14 under substantial compression. As the compression applied by the head 12' is increased, the members 14 are expanded radially from the full line position to the dotted line positi'on shown in" Fig; 4'. This expanding or spreading action causes the diameter of the cylindrical cutting part of the tool to be increased so as to either compensate for wear of the working surface or to condition the tool for lapping the internal walls of cylinders or apertures of various sizes.

Alternate members 14 formed of comparatively hard and soft metal respectively may be used: if desired in this form of my invention, but soft metal is advantageously used because the granular particles of abrasive which escape from between the super-imposed frusto'conical members become embedded in soft metal more readily.

Although but several-specific embodiments of this invention have herein been shown and described, itwill be understood that various changes including the size, shape and arrangement of parts may be made without departingfrom. the spirit of my invention and it is not my intention to limit its scope other than by the terms of the appended claims.

I claim 1. In a lap, a rigid fabricated cylinder comprising a plurality of superimposed metal members, films comprising substantially free particles of diamond dust between said members aligned with and exposed at the outer periphery of said cylinder, and means clamping said members together.

2. A lap comprising a shank, a stem on said shank, a plurality of rigid annular metal members mounted on said stem having their outer peripheries substantially in alignment with each other, deposits of substantially free particles of abrasive material empacked between said annular members and exposed at the outer peripheries thereof, and means on the outer end of said stem for retaining said annular members and abrasive material in compressed engagement upon an extremity of said shank.

3. A lap comprising a stem having a shoulder, a plurality of superimposed metal annular rigid members mounted on said stem each having a central aperture for receiving said stem, means clamping said members upon said shoulder, the peripheral portions of said members being inflexible and protruding but slightly beyond said shoulder and a film of abrasive material comprising a binder and granular substance on corresponding sides of said members at the outer periphery thereof.

4. In a lap, a fabricated cylinder comprising super-imposed comparatively hard and comparatively soft metal annular members respectively, and abrasive material between said members.

5. In a lap, a fabricated cylinder comprising alternate layers of comparatively hard and comparatively soft meta-l respectively, a film of abrasive material between adjacent sides of said layers, and means firmly clamping said layers together.

6. A lap, comprising a. support, a plurality of radially yieldable frusto-conical members mounted on said support, abrasive material between adjacent sides of said members, and means on said support for retaining said members together in clamped radially expanded positions.

7 A lap comprising a shank, a stem threaded on one end of said shank, a plurality of superimposed yieldable frusto-conical members-mounted on said stem, each having a central aperture for receiving the latter, and means on said stem for retaining said members in a clamped radially expanded position.

8. A lap comprising a shank, a stem threaded on one end of said shank, a plurality of superimposed yieldable frusto-conical members mounted on said stem, each having a central aperture for receiving the latter,

abrasive material between adjacent sides of said members, and means on said stem for retaining said members in a clamped radially expanded position.

9. In a lap, a cutting cylinder comprising a plurality of frusto-conical yieldable members, a film on the outer edge portions of the sides of said members consisting of a binder and diamond dust, and adjustable means bearing between the external and internal sides of the outermost members respectively for expanding said members radially soas to vary the diameter of said cylinder.

10. In a lap, a fabricated cylinder comprising superimposed radially expansible members, abrasive material between adjacent sides of said members exposed at the periphery of said cylinder, and variable means clamping said members together, said means being adapted to expand said members radially so as to change the diameter of said cylinder.

11. An internal lap comprising a shank having an aperture in one end thereof, a stem threaded in said aperture, a plurality of superimposed frusto-conical members mounted on said stem, the outer portions of said members being slotted radially, a seat on said shank engaging the external side of one of the outermost members, and a head on said stem bearing upon the internal side of the other outermost member, said stem being adj ustable for expanding said members radially so as to vary the diameters thereof.

12. An internal lap comprising a shank having an aperture in one end thereof, a stem threaded in said aperture, a plurality of superimposed frusto-conical members mounted on said stem, the outer portions of said members being slotted radially, abrasive material between adjacent members exposed at the outer peripheries thereof, a seat on said shank engaging the external side of one of the outermost members, and a head on said stem bearing upon the internal side of the other outermost member, said stem being adj ustable for expanding said members radially so as to vary the diameters thereof.

13. In a lap, a support, a fabricated cylinder on said support including a. plurality of radially expansible frusto-conical members, alternate members comprising comparatively hard and comparatively soft metal respectively, a film of abrasive material between adjacent sides of said members, and means on said support for retaining said members in clamped radially expanded positions.

CONRAD F. BIRGBAUER. 

